毛竹四季笋山笋竹双高产林分研究初报

为了进一步探索笋用毛竹林丰产规律,提高竹林的经济效益,我所进行了笋用毛竹林的生长规律、培育技术和经济效益的调查研究。现初步总结如下:     

大径毛竹林笋期生长规律的初步研究

通过二个出笋大年和多次重复的对比观察，获得了大量数据，表明大径毛竹林在出笋、退笋、成竹规律的过程中，与不同经营水平竹林的差异，这些差异表现了大径竹林具有优良林分结构的调节效应，促进了大径阶新竹株的进一步提高。对这些规律的研究，可为大径毛竹林的合理经营，促进国产、稳产提供理论依据和生产指导作用。     

浙江遂昌毛竹鞭笋丰产培育技术

为了发挥毛竹林生产潜力,增加竹农经济收入,在多年实践研究的基础上总结出一套毛竹鞭笋丰产培育技术。研究认为：在毛竹笋材两用林中采挖鞭笋,不会影响整体的竹鞭鞭径和竹鞭总量生长;毛竹林地覆盖稻草和砻糠能显著提高第3年的鞭笋产量;培育高产鞭笋的最佳施肥时间为每年的5月;鞭笋采收时间为5-10月。毛竹鞭笋丰产培育技术可在毛竹笋材两用林经营中推广应用。     

毛竹林笋期管护及合理挖笋

阐述毛竹鞭笋、冬笋、春笋及大年笋、小年笋在生长过程中的相互关系，针对毛竹林笋期各不同阶段特点，提出科学经营管护及合理挖笋的技术措施，供生产上应用参考。     

毛竹出笋数学模型的研究

对毛竹林不同经营措施进行毛竹出笋试验研究,采用8种回归方程进行拟合比较,找出适合新罗区的最优模型。旨在用于预测毛竹林出笋情况,以便指导毛竹林生产培育与竹笋采收。     

毛竹林生态系统可持续经营研究进展

竹子是森林资源重要的组成部分,其中毛竹集生态、经济、社会效益于一体,是中国重要的的优良竹种。毛竹是当今世界上生长快、产量高、可再生能力强的自然资源之一。应对当今世界面临的环境和社会问题,毛竹具有巨大的潜力。受经营目标及利益驱动的影响,当前毛竹林可持续经营已受到挑战。研究系统阐述了生态系统经营的概念、毛竹林生态系统经营的现状和面临的问题、毛竹林生态系统的可持续经营等内容,同时从竹林健康监测评价、竹林生态系统服务功能、竹林生态系统的可持续经营指标体系的构建和竹林生态系统的修复与维护4个方面,对国内外关于毛竹林生态系统可持续经营研究现状进行介绍,并且对未来经营的发展趋势作出了预判与展望。     

地面覆盖对毛竹生长影响的初步研究

研究了地面覆盖对毛竹林出笋状况及地下结构的影响,结果表明：采用覆盖技术后,毛竹出笋时间显著提前,笋产量大大提高;覆盖后样方内竹鞭总长度为740.48cm/m2,幼壮龄鞭占总鞭长的35.95%,和未覆盖竹林相比,鞭段数有所增加,总鞭长和幼壮龄鞭的比例有所下降;覆盖毛竹林鞭侧芽的总数少于未覆盖毛竹林,但休眠芽中的活芽高于未覆盖竹林。表明连续覆盖2年后的毛竹林地下鞭还具有丰产潜力。     

毛竹平衡施肥促丰产

毛竹是我国栽培面积最大的优良的速生用材竹种和经济竹种.在毛竹林的经营中,为促使毛竹丰产、高产,需要追施肥料来补充养分.毛竹林施用的肥料有专用肥、复混肥、微肥和采用先进的方法,达到毛竹经营的长久效益,养分平衡和地力维持.土壤肥力状况是毛竹林合理施肥、集约经营的重要依据.不同生产力水平、不同经营时期的毛竹林合理施肥,表现出毛竹林土壤养分动态变化.低产毛竹林的主要原冈是土壤20～40cm土层有效养分总储量低,而施肥能提高出笋数量,并使发笋期提早和延长,实践证明,氮磷钾合理配比施肥效果明显.平衡施肥能有效提高新竹眉径,使竹子明显增粗.     

不同经营措施对毛竹林春笋生长的影响

开展3种经营措施（浅锄+穴施复合肥、浅锄、不抚育管理）对毛竹春笋生长的影响试验。结果表明：不同的经营措施对毛竹林的出笋期、春笋产量和成竹数均有极显著的影响,对平均退笋高度影响不显著。采用劈草、浅锄、施肥和喷灌等经营措施的毛竹林出笋最早、结束出笋最迟、出笋周期最长、出笋量也最多,同时成竹数和成竹率也最高。     

大小年经营竹林与花年经营竹林笋,竹产量对比试验

大小年经营的毛竹林改制为花年竹林，花年经营的毛竹林平均笋产量比大小年经营的增加１５０．５９％，提高２．５倍，笋竹两项经济收入比大小年经营的毛竹林增加１９０．３％，提高２．９倍。     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.